It is known (for example from US 2004/0172532) to provide a consumable item, such as a ink cartridge, with an integrated circuit chip enabling it to be authenticated by an apparatus, such as a printer. The chip stores a private key of a public/private key pair, and includes functionality for responding to a challenge issued by the apparatus by encrypting an element included in the challenge using the stored private key, and returning the encrypted element to the challenging apparatus. The apparatus decrypts the returned encrypted element using the public key associated with an authentic consumable item and only if the result of this decryption matches the original element included in the challenge does the apparatus accept the consumable item as a genuine one.
Using such an arrangement, it is possible to ensure that only genuine consumable items are used with an apparatus. This has advantages for a manufacturer providing warranty services because the manufacturer can be certain that any defects arising in the apparatus are not as a result of consumable items of doubtful provenance and quality having been used for the apparatus. However, a user of the apparatus may feel aggrieved that his/her freedom to use consumable items from any source has been removed.
There are other situations where different parties have different interests in relation to controlling the source of consumable items to be used in an apparatus. For example, a user may opt to obtain possession of a printer through a lease-purchase arrangement by which legal title to the apparatus only passes to the user after a predetermined lease period. During the lease period the lessor will wish to ensure that the consumable items used are not harming the apparatus which the lessor still owns; however, the user will always wish to have a free choice of the source from which he/she obtains consumable items for the apparatus as this ensures that the price is kept reasonable through operation of market forces.
It is an object of the present invention to provide increased flexibility in the management of an apparatus using a consumable item, of given type, requiring occasional renewal.